Liquid cartridge and liquid supplying device

ABSTRACT

A liquid cartridge detachably loadable in a cartridge loading section of a liquid supplying device is provided. The liquid cartridge includes: a main body defining therewithin a liquid accommodation chamber storing liquid therein, the liquid accommodation chamber having a light-transmission portion transmitting light therethrough; a moving member disposed within the liquid accommodation chamber and configured to move in accordance with an amount of the liquid; a light-emitting element configured to emit light and move in conjunction with the movement of the moving member; and a light outlet configured to irradiate the light emitted from the light-emitting element toward outside of the main body via the light-transmission portion.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. application Ser.No. 13/050,916 filed Mar. 17, 2011 which claims priority from JapanesePatent Application No. 2010-072377 filed Mar. 26, 2010. The entirecontent of the priority application is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a liquid cartridge that stores liquidtherein and a liquid supplying device that accommodates therein theliquid cartridge.

BACKGROUND

There have been various proposals for detecting residual amounts ofliquid stored in liquid cartridges. According to one of such techniques,a residual amount of liquid is detected by using a photosensor(photointerrupter) including a light-emitting element and alight-receiving element.

A technique to detect an amount of ink in an ink cartridge loaded in acartridge loading portion of an inkjet printer is also known. Such anink cartridge has a main body serving as an ink chamber, an arm movablyprovided within the ink chamber, a float and a shielding plate. Thefloat is connected to one end of the arm so as to move in a verticaldirection in accordance with an amount of ink in the ink chamber. Theshielding plate is connected to another end of the arm so as to move inconjunction with vertical movement of the float.

The cartridge loading portion is provided with a sensor including alight-emitting element and a light-receiving element. The light-emittingelement emits light toward the loaded ink cartridge, and thelight-receiving element receives the light that was transmitted throughthe ink cartridge. When more than a predetermined amount of ink is leftin the ink chamber, the shielding plate is at such a position that theshielding plate shuts off the light from the light-emitting element.Therefore, the light-receiving element does not receive the light fromthe light-emitting element through the ink cartridge. On the other hand,when the ink decreases below the predetermined amount, the shieldingplates moves in accordance with the movement of the float so that theshielding plate no longer shuts off the light. As a result, the lightemitted from the light-emitting element passes through the ink cartridgeand is received at the light-receiving element. With this configuration,whether the predetermined amount of ink is left within the ink chambercan be detected based on changes in an amount of light received at thelight-receiving element.

SUMMARY

However, in the above-described configuration, the position of thesensor (specifically, the position of the light-emitting element) isfixed for detecting the position of the shielding plate that moves inaccordance with the amount of ink in the ink cartridge. Therefore, theabove-described configuration only detects whether or not the shieldingplate is positioned to shut off the light from the light-emittingelement, i.e., whether or not the residual amount of ink is more thanthe predetermined amount (a single level of a liquid surface). In otherwords, more than two levels of liquid surfaces cannot be detected.Increasing a number of sensors can solve this problem, but employing anincreased number of sensors directly leads to an increase in costs ofthe inkjet printer.

In view of the foregoing, it is an object of the present invention toprovide a liquid cartridge and a liquid supplying device capable ofdetecting residual amounts of liquid at a plurality of levels.

In order to attain the above and other objects, the present inventionprovides a liquid cartridge detachably loadable in a cartridge loadingsection of a liquid supplying device. The liquid cartridge includes: amain body defining therewithin a liquid accommodation chamber storingliquid therein, the liquid accommodation chamber having alight-transmission portion transmitting light therethrough; a movingmember disposed within the liquid accommodation chamber and configuredto move in accordance with an amount of the liquid; a light-emittingelement configured to emit light and move in conjunction with themovement of the moving member; and a light outlet configured toirradiate the light emitted from the light-emitting element towardoutside of the main body via the light-transmission portion.

According to another aspect of the present invention, there is provideda liquid supplying device that includes a liquid cartridge and acartridge loading section configured to accommodate therein the liquidcartridge. The liquid cartridge includes: a main body definingtherewithin a liquid accommodation chamber storing liquid therein, theliquid accommodation chamber having a light-transmission portiontransmitting light therethrough; a moving member disposed within theliquid accommodation chamber and configured to move in accordance withan amount of the liquid; a light-emitting element configured to emitlight and move in conjunction with the movement of the moving member;and a light outlet configured to irradiate the light emitted from thelight-emitting element toward outside of the main body via thelight-transmission portion.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a plan view schematically illustrating a configuration in thevicinity of an ink supplying device that is common to all embodimentsand modifications of the present invention;

FIG. 2 is a vertical cross-sectional view of the ink cartridge accordingto a first embodiment of the present invention taken along a planeincluding a loading direction of the ink cartridge;

FIG. 3A is a vertical cross-sectional view of the ink cartridge and acartridge loading portion according to the first embodiment, wherein theink cartridge stores a sufficient amount of ink therein;

FIG. 3B is a vertical cross-sectional view of the ink cartridge and thecartridge loading portion according to the first embodiment, wherein theink cartridge stores a small amount of ink therein;

FIG. 4 is a vertical cross-sectional view of an ink cartridge and acartridge loading portion according to a first modification of the firstembodiment of the present invention;

FIG. 5 is a vertical cross-sectional view of the ink cartridge accordingto the first embodiment and a cartridge loading portion according to asecond modification of the first embodiment of the present invention;

FIG. 6 is a vertical cross-sectional view of the ink cartridge accordingto the first embodiment and a cartridge loading portion according to athird modification of the first embodiment of the present invention;

FIG. 7 is a vertical cross-sectional view of an ink cartridge and acartridge loading portion according to a fifth modification of the firstembodiment of the present invention;

FIG. 8 is a vertical cross-sectional view of an ink cartridge and acartridge loading portion according to a seventh modification of thefirst embodiment of the present invention;

FIG. 9 is a vertical cross-sectional view of an ink cartridge and acartridge loading portion according to a ninth modification of the firstembodiment of the present invention;

FIG. 10 is a vertical cross-sectional view of an ink cartridge accordingto a tenth modification of the first embodiment of the present inventionand the cartridge loading portion according to the first embodiment;

FIG. 11 is a vertical cross-sectional view of an ink cartridge and acartridge loading portion according to an eleventh modification of thefirst embodiment of the present invention; and

FIG. 12 is a vertical cross-sectional view of an ink cartridge and acartridge loading portion according to a second embodiment of thepresent invention taken along a plane including a loading direction ofthe ink cartridge;

FIG. 13A is a vertical cross-sectional view of the ink cartridge and thecartridge loading portion according to the second embodiment, whereinthe ink cartridge stores a sufficient amount of ink therein;

FIG. 13B is a vertical cross-sectional view of the ink cartridge and thecartridge loading portion according to the second embodiment, whereinthe ink cartridge stores a small amount of ink therein; and

FIG. 14 is a vertical cross-sectional view of an ink cartridge and acartridge loading portion according to a variation of the secondembodiment, wherein the seventh modification of the first embodiment isapplied to the ink cartridge and the cartridge loading portion of thesecond embodiment.

DETAILED DESCRIPTION

First, a configuration in the vicinity of an ink supplying device 8 ofan inkjet printer 1 that is common to all embodiments and modificationsof the present invention will be described with reference to FIG. 1. Theterms “upward”, “downward”, “upper”, “lower”, “above”, “below”,“beneath”, “right”, “left”, “front”, “rear” and the like will be usedthroughout the description assuming that the inkjet printer 1 isdisposed in an orientation in which it is intended to be used.

In the inkjet printer 1, a carriage 2, an inkjet head 3, four sub tanks4 a, 4 b, 4 c, 4 d, the ink supplying device 8 and a sheet conveyingunit 6 are provided, as shown in FIG. 1. Four ink cartridges 5 a, 5 b, 5b, 5 c 5 d according to all embodiments and modifications are detachablyloadable in the ink supplying device 8.

The carriage 2 is adapted to make reciprocal movements with respect to ascanning direction indicated by a two-way arrow in FIG. 1, which isparallel to a left-to-right direction in FIG. 1. Two guide shafts 17 aredisposed and extend in a direction parallel to the left-to-rightdirection for guiding the reciprocal movements of the carriage 2 alongthe guide shafts 17. An endless belt 18 is connected to the carriage 2and a carriage drive motor 19 is disposed for driving the endless belt18. The carriage 2 is thus allowed to reciprocally move with respect tothe scanning direction in conjunction with movement of the endless belt18.

The carriage 2 includes the inkjet head 3 and the four sub tanks 4 a, 4b, 4 c and 4 d. The inkjet head 3 has a lower surface (a surfaceopposite to a top surface shown in FIG. 1) on which a plurality ofnozzles is provided for ejecting ink droplets onto a sheet P conveyed bythe sheet conveying unit 6. The sub tanks 4 a, 4 b, 4 c, 4 d arejuxtaposed in the scanning direction and are integrally connected to atube joint 20. Four flexible tubes 11 are connected to the tube joint 20so that each of the four sub tanks 4 a, 4 b, 4 c, 4 d can be connectedto each of the four ink cartridge 5 a, 5 b, 5 c, 5 d loaded in the inksupplying device 8 via the corresponding tubes 11.

The ink supplying device 8 includes a holder 10 in which four cartridgeloading portions 7 are provided for accommodating therein respective oneof the four ink cartridges 5 a, 5 b, 5 c, 5 d. The ink cartridges 5 a, 5b, 5 c, 5 d respectively store one of four colors of ink: black, yellow,cyan, and magenta, for example. All the four ink cartridges 5 a, 5 b, 5c, 5 d have configurations identical to one another except that eachaccommodates ink of a different color. Each of the four ink cartridges 5a, 5 b, 5 c, 5 d is detachably insertable into the correspondingcartridge loading portion 7 of the holder 10. In this way, the inkcartridges 5 a, 5 b, 5 c, 5 d are detachably loadable in and unloadedfrom the holder 10. Each of the four colors of ink stored in one of theink cartridges 5 a, 5 b, 5 c, 5 d is supplied to one of the four subtanks 4 a, 4 b, 4 c, 4 d via the corresponding tubes 11, temporarilystored in respective sub tanks 4 a, 4 b, 4 c, 4 d, and then supplied tothe inkjet head 3. While the inkjet head 3 makes reciprocal movements inthe scanning direction along with the carriage 2, the ink supplied tothe inkjet head 3 is ejected therefrom in a form of fine droplets ontothe sheet P via the plurality of nozzles.

The sheet conveying unit 6 serves to convey the sheet P in a sheetconveying direction as indicated in FIG. 1. The sheet conveying unit 6includes two sheet feed rollers 25 and 26. The sheet feed roller 25 isdisposed upstream of the inkjet head 3, while the sheet feed roller 26is disposed downstream of the inkjet head 3 in the sheet conveyingdirection. The sheet feed roller 25 is driven by a sheet feed motor 27,and the sheet feed roller 26 is driven by a sheet discharge motor 28. Inthe sheet conveying unit 6, the sheet feed roller 25 conveys the sheet Pto the inkjet head 3 in the sheet conveying direction (toward downwardin FIG. 1), and the sheet feed roller 26 discharges the sheet P on whichan image and/or texts are formed by the inkjet head 3 further downwardin FIG. 1.

Next, an ink cartridge 5 according to a first embodiment of the presentinvention will be described with reference to FIGS. 2 to 3B. The inkcartridge 5 is an illustrative example of the four ink cartridges 5 a, 5b, 5 c, 5 d loadable in the inkjet printer 1. In the followingdescription, a left side of FIG. 2 will be defined as a front side and aright side of FIG. 2 will be defined as a rear side. The ink cartridge 5is loaded in the holder 10 in a loading direction (indicated by an arrowin FIG. 2), i.e., toward the front side, and unloaded from the holder 10in an unloading direction opposite to the loading direction i.e., towardthe rear side in FIG. 2.

The ink cartridge 5 includes a main body 30 that defines an ink chamber33 therein, and an arm member 31 movably disposed within the ink chamber33.

The main body 30 is formed of a material having light transmissivecharacteristic, such as synthetic resin. The ink chamber 33 stores inktherein and is formed within the main body 30.

The main body 30 has a rear wall 34 (trailing side in the loadingdirection) that projects outward (rearward), and has an arcuate-shape(circular are shape) in vertical cross-section. The main body 30 has afront wall 36 on which an ink outlet port 37 and an air communicationport 38 are formed, as shown in FIG. 2. The ink outlet port 37 isprovided at a lower end of the front wall 36 for allowing ink in the inkchamber 33 to flow out of the ink chamber 33. A ring-shaped sealingmember 39 is provided on the front wall 36 such that the sealing member39 surrounds the ink outlet port 37. The sealing member 39 is formed ofa material having a sealing capability, such as rubber. The aircommunication port 38 is disposed at an upper end of the front wall 36.The air communication port 38 is in fluid communication with an upperspace formed within the ink chamber 33 to introduce an external air intothe ink chamber 33.

The arm member 31 is movably disposed within the ink chamber 33. The armmember 31 includes a float 40, an arm 41, a pivot-center portion 42 anda protruding portion 43, as shown in FIG. 2. The arm 41 has one endconnected to one side of the float 40 and another end connected to thepivot-center portion 42. The protruding portion 43 has one end connectedto another side of the float 40, the another side of the float 40 beingopposite to the one side to which the arm 41 is connected. In this way,the float 40, the arm 41, the pivot-center portion 42 and the protrudingportion 43 integrally constitute the arm member 31. The float 40 and theprotruding portion 43 correspond to a moving member of the presentembodiment.

The pivot-center portion 42 has a spherical shape as a whole andtherefore a substantially circular shape in vertical cross-section, asshown in FIG. 2. The pivot-center portion 42 has a central portionthrough which a shaft 44 penetrates. The shaft 44 is supported to a pairof side walls (now shown) of the main body 30 (walls disposed inparallel to a plane of FIG. 2). With this configuration, the float 40(the arm member 31) is pivotally movable about the shaft 44 with respectto a vertical direction.

As shown in FIG. 2, the main body 30 has an upper wall 35 and a bottomwall 32 whose inner surface is formed with a protruding portion at aposition in confrontation with the pivot-center portion 42. Theprotruding portion protrudes upward from the inner surface of the bottomwall 32 and has a smoothly inwardly-curved concave-shaped surface (topsurface) 32 a in conformance with the arcuate-shaped (circular arcshaped) outline of the pivot-center portion 42. The concave-shapedsurface 32 a and the pivot-center portion 42 define a prescribed gaptherebetween.

The protruding portion 43 protrudes from a portion 52 of the float 40 ina direction coincident with an extension of the arm 41, the portion 52being opposite to a portion 51 of the float 40 to which the arm 41 isconnected. The protruding portion 43 has a tip end 53 facing and spacedaway from the rear wall 34 by a prescribed distance, for example, from0.5 mm to 1 mm.

Within the ink chamber 33, two stoppers 46, 47 are provided forrestricting the pivotal movement of the float 40 (the arm 41). Thestopper 46 serves to prevent the float 40 (the arm 41) from pivotallymove further upward (an upper-limit position of the float 40 indicatedby a solid line in FIG. 2), and the stopper 47 serves to prevent thefloat 40 (the arm 41) from pivotally move further downward (alower-limit position of the float 40 indicated by a two-dashed chainline in FIG. 2).

More specifically, when sufficient ink is stored in the ink chamber 33(i.e., an ink level is higher than or equal to a first liquid level L1shown in FIG. 3A), the arm 41 is in contact with the stopper 46 due tomoment acting on the arm 41 in a counterclockwise direction caused bybuoyancy of the float 40. As a result, the float 40 and the arm 41 arerestricted from moving further upward and maintained at the upper-limitposition, as show in FIG. 3A. When the ink decreases and the ink levelfalls below the first liquid level L1, a portion of the float 40 startsto appear from the ink surface, and the buoyancy acting on the float 40starts to decrease. Therefore, as the ink level lowers, the float 40 andthe arm 41 pivotally move in a clockwise direction in FIG. 3. In themeantime, in accordance with the pivotal movement of the float 40 andthe arm 41 in the vertical direction, the protruding portion 43 movesalong the rear wall 34 (more specifically, an inner wall of the rearwall 34), while maintaining the prescribed distance therefrom. When theink is further reduced and the ink chamber 33 becomes near empty (i.e.,the ink level falls below a second liquid level L2 shown in FIG. 3B),the protruding portion 43 contacts the stopper 47. The arm member 31 isthus restricted from moving further downward and maintained at thelower-limit position, as shown in FIG. 3B.

The pivot-center portion 42 is positioned to face a light-emittingelement 63 that is disposed at a bottom wall section 66 of the cartridgeloading portion 7, as shown in FIGS. 3A and 3B. The arm 41 receiveslight emitted from the light-emitting element 63, guides the incidentlight to the float 40 through the arm 41, and the protruding portion 43finally irradiates the light from the tip end 53 to outside of the mainbody 30. More specifically, as illustrated by heavy lines in FIGS. 3Aand 3B, the pivot-center portion 42 has a lower portion 50 inconfrontation with the concave-shaped surface 32 a of the protrudingportion of the bottom wall 32. This lower portion 50 haslight-transmissive characteristics and is adapted to receive the lightfrom the light-emitting element 63. This lower portion 50 thus serves asan inlet of the light. The portion 51 connecting the arm 41 and thefloat 40, and the portion 52 connecting the float 40 and the protrudingportion 43 also have light-transmissive characteristics. The tip end 53of the protruding portion 43 also has light-transmissive characteristicsand serves as an outlet of the light. Other portions of the arm member31 (portions other than the light inlet 50, the connecting portions 51,52 and the light outlet 53) have inner surfaces that can reflect light,and correspond to a third portion of the present invention. The portions51, 52 correspond to a first portion and a second portion of the presentembodiment respectively.

With the above-described configuration, light emitted from thelight-emitting element 63 enters into the arm member 31 via the lightinlet 50 of the pivot-center portion 42, and is then guided to the float40 while being reflected by the inner surfaces of the arm 41, and isfinally irradiated from the light outlet 53 of the protruding portion 43toward the rear wall 34 of the main body 30. A possible light path alongwhich the incident light travels through the arm member 31 is shown suchas a thick zigzag line in FIGS. 3A and 3B. The rear wall 34 correspondsto a light-transmission portion of the present embodiment. The arm 41corresponds to a light guiding portion of the present embodiment.

The protruding portion 43 may be dispensed with. In this case, the lightoutlet 53 may be formed on the float 40 directly. However, since theprotruding portion 43 protruding from the float 40 is provided with thelight outlet 53 in the present embodiment, light can travel through theprotruding portion 43 extending in one direction before being irradiatedoutside of the main body 30. Therefore, incident light is allowed totravel in a relatively straightforward manner until being irradiatedfrom the light outlet 53, compared to the case in which the protrudingportion 43 is not provided. As a result, the light irradiated from thelight outlet 53 is hard to be radiated.

The reflectivity of the inner surfaces of the arm member 31 can berealized by performing a reflexible coating, such as nickel, onprescribed regions of the inner surfaces of the arm member 31.Alternatively, portions that require light reflectivity may have adouble-layered structure: a core layer having a high refractive index iscoated with another layer having a low refractive index. With thisdouble-layered structure, light can travel based on total internalreflection, that is, from the layer with high refractive index towardthe layer with low refractive index.

Next, details of the holder 10 (the cartridge loading portion 7) will bedescribed with reference to FIGS. 3A and 3B. As described before, theholder 10 is provided with four cartridge loading portions 7 aligned ina direction parallel to the scanning direction (see FIG. 1). Since thefour cartridge loading portions 7 have configurations identical to oneanother, one of the cartridge loading portions 7 will only be describedhereinafter.

As shown in FIGS. 3A and 3B, the cartridge loading portion 7 definestherewithin a cartridge accommodating chamber 60, and includes a cover61. The cartridge accommodating chamber 60 has an opening facingrearward, and the cover 61 is configured to cover the opening to coverthe ink cartridge 5 accommodated within the cartridge accommodatingchamber 60. The ink cartridge 5 is inserted into the cartridgeaccommodating chamber 60 through the opening when the cover 61 isopened.

The holder 10 has a front wall section 65 constituting the cartridgeaccommodating chamber 60. The front wall section 65 is formed with anink introduction path 62 extending in the loading direction andpenetrating through the front wall section 65. The ink introduction path62 is connected to the inkjet head 3 via one of the tubes 11. The inkintroduction path 62 is in fluid communication with the ink outlet port37 of the ink cartridge 5 via the sealing member 39 when the inkcartridge 5 is accommodated within the cartridge accommodating chamber60. In this way, the ink flowing out of the ink chamber 33 through theink introduction path 62 is introduced to the inkjet head 3 via the tube11.

The holder 10 has an upper wall section 69 and the bottom wall section66 constituting the cartridge accommodating chamber 60. Thelight-emitting element 63 is disposed on the bottom wall section 66 foremitting light upward toward the loaded ink cartridge 5. Morespecifically, as shown in FIG. 3A, the light-emitting element 63 isdisposed at a position vertically below the concave-shaped surface 32 aformed on the bottom wall 32 of the ink cartridge 5. In other words, thelight inlet 50 provided on the pivot-center portion 42 of the arm member31 is in confrontation with the light-emitting element 63 so that thelight emitted from the light-emitting element 63 can be received at thelight inlet 50. The light emitted from the light-emitting element 63passes through the bottom wall 32 of the ink cartridge 5 and isirradiated toward the arm member 31 via the concave-shaped surface 32 a.The irradiated light travels through the ink available between the armmember 31 and the bottom wall 32, and enters into the arm member 31through the light inlet 50. The light is then guided within and alongthe arm member 31 to the float 40, and finally irradiated outside of theink cartridge 5 from the light outlet 53 of the protruding portion 43extending from the float 40.

As described above, the light is irradiated toward outside of the mainbody 30 of the ink cartridge 5 from the light outlet 53 that moves inaccordance with the amount of the ink in the ink chamber 33. Therefore,a position on the rear wall 34 from which the light from the lightoutlet 53 is emanated before being irradiated outward can vary dependingon the residual amounts of ink within the ink chamber 33.

Specifically, as shown in FIG. 3A, when the amount of ink is more thanfirst liquid level L1, the float 40 is positioned at its upper-limitposition. Therefore, the light irradiated from the light outlet 53passes an upper portion of the rear wall 34 and exits diagonally upwardand rearward. When the ink is reduced to fall below the second liquidlevel L2, as shown in FIG. 3B, the float 40 is at the lower-limitposition. The light passes a lower portion of the rear wall 34 and exitshorizontally toward rearward.

The cover 61 has an arcuate-shape (circular are shape) in verticalcross-section in conformance with the rear wall 34 of the ink cartridge5 that is loadable in the cartridge accommodating chamber 60. The cover61 has a lower end that is pivotably movably supported to the bottomwall section 66. The cover 61 is therefore pivotally movable between anopen position (not shown) in which the cartridge accommodating chamber60 is exposed and a closed position (FIGS. 3A and 3B) in which the rearwall 34 of the loaded ink cartridge 5 is covered. The cover 61 isprovided with an engaging portion 61 a that is engagable with the upperwall portion 69 of the holder 10. The cover 61 is locked at the closedposition due to the engagement of the engaging portion 61 a with theupper wall section 69.

The cover 61 has an inner surface on which two light-receiving elements67, 68 are provided. The two light-receiving elements 67, 68 aredisposed at positions different from each other in the verticaldirection along which the float 40 pivotally moves. More specifically,the light-receiving element 67 is disposed at a position facing and incontact with the upper portion of the rear wall 34 of the ink cartridge5 when the cover 61 is closed. The light-receiving element 68 isdisposed at a position facing and in contact with the lower portion ofthe rear wall 34 of the ink cartridge 5 when the cover 61 is closed.With this arrangement, the inkjet printer 1 can detect two kinds ofliquid levels (L1 and L2) based on signals outputted from thelight-receiving elements 67, 68 in accordance with amounts of lightreceived at the light-receiving elements 67, 68. That is, thelight-receiving elements 67, 68 are aligned in the vertical directionalong which the light outlet 53 (the float 40 and the protruding portion43) moves in accordance with the amount of liquid within the ink chamber33. The vertical direction corresponds to a moving direction of thepresent invention.

Specifically, when the residual amount of ink is more than the firstliquid level L1 and the float 40 is at the upper-limit position as shownin FIG. 3A, the light-receiving element 67 receives the light irradiatedfrom the light outlet 53. The light-receiving element 67 outputs asignal indicating that a sufficient amount of ink is left in the inkchamber 33 in response to receipt of the light from the light outlet 53.The inkjet printer 1 can therefore detect that the sufficient mount ofink is left in the ink chamber 33 based on the signal from thelight-receiving element 67. On the other hand, when the residual amountof ink is smaller than the second liquid level L2 and the float 40reaches the lower-limit position as shown in FIG. 3B, thelight-receiving element 68 receives the light emitted from the lightoutlet 53. The inkjet printer 1 can therefore detect that there islittle amount of ink left in the ink chamber 33 based on a signaloutputted from the light-receiving element 68 in response to receipt ofthe light at the light-receiving element 68.

A user manually operates to open or close the cover 61 for mounting ordismounting the ink cartridge 5. If the user may touch either one orboth of the light-receiving elements 67, 68 upon operation of the cover61, sensitivity of the touched light-receiving elements 67, 68 could belowered due to contamination. However, since the light-receivingelements 67, 68 are disposed at the inner surface of the arcuate-shapedcover 61 in the first embodiment, as long as the user operates normally,there is a lower possibility that the user may touch either thelight-receiving element 67 or the light-receiving element 68. Further,since the light-receiving elements 67, 68 are arranged to be in contactwith the rear wall 34 of the ink cartridge 5, the ink cartridge 5 can bereliably fixed within the cartridge loading portion 7. It should benoted that, in view of the single function to receive the lightirradiated from the light outlet 53, the light-receiving elements 67, 68may simply be respectively positioned to face the rear wall 34 of theink cartridge 5, and may not necessarily be brought into contact withthe rear wall 34 of the ink cartridge 5.

With the above-described configuration, depending on the lightirradiated out of the light outlet 53 in accordance with the remainingamounts of ink in the ink chamber 33, two different positions of thefloat 40, namely, two different ink levels (the first liquid level L1and the second liquid level L2), can be detected at the inkjet printer1. Although two light-receiving elements 67, 68 are provided in thefirst embodiment, more than two light-receiving elements may bevertically arranged on the cover 61 so that more than two ink levels canbe detected.

According to the conventional ink level detection system in which onlyone ink level can be detected, the detected amount of ink is such anamount at which the float starts to move due to the float's exposurefrom a liquid surface of the ink (corresponding to the first liquidlevel L1 in the first embodiment). Therefore, such a state where thereis little amount of ink (corresponding to the second liquid level L2 inthe first embodiment) cannot be detected. In other words, since the inkstill remains within the ink cartridge even after a near empty state (astate where a substantial amount of ink has decreased) has beendetected, the conventional printer is required to predict how much inkis left in order to use up the ink remained in the ink cartridge.Specifically, the conventional printer first starts to predict amountsof ink consumed at the inkjet head (amount of ink ejected from thenozzles, amount of ink discharged during maintenance and so on) afterdetection of the near empty state, and then accumulates the presumed inkconsumption amounts to predict the residual amount of ink in the inkcartridge. However, the presumed ink consumption amount sometimes variesfrom an amount of ink that has actually been consumed. Improved accuracyin detecting the residual amount of ink has therefore been sought for.

In contrast, in the above-described first embodiment, the position ofthe float 40 can be detected in accordance with the residual amount ofink. The state of FIG. 3B in which there is almost no ink left in theink chamber 33 can also be detected directly. Therefore, the ink in theink cartridge 5 can all be used up.

Further, in the first embodiment, the light-emitting element 63 isdisposed outside of the ink chamber 33 (on the bottom wall section 66 ofthe cartridge loading portion 7), not within the ink chamber 33.Therefore, wirings for supplying power to the light-emitting element 63can be easily connected to the light-emitting element 63, compared to acase where the light-emitting element 63 is disposed on the float 40within the ink chamber 33. Electrical configurations for supplying powerto the light-emitting element 63 thus become easier in the firstembodiment.

Further, when the remaining amount of ink is sufficient (more than thefirst liquid level L1), the light is irradiated upward (diagonallyupward) from the light outlet 53 of the protruding portion 43 protrudingdiagonally upward from the float 40. The light-receiving element 67 isdisposed substantially upward of the ink cartridge 5 (specifically, atan upper portion of the cover 61 that can be in confrontation with theupper portion of the rear wall 34 from which the irradiated light isemanated) such that the light-receiving element 67 can receive the lightirradiated from the light outlet 53.

If there is ink between the light outlet 53 and the main body 30 (therear wall 34) of the ink cartridge 5, the amount of ink that can bereceived at the light-receiving element 67 inevitably decreases.However, in the first embodiment, since the ink chamber 33 is providedwith the air communication port 38 for introducing air into the inkchamber 33, a layer of air constantly exits at an upper portion of theink chamber 33 even though the sufficient amount of ink is stored withinthe ink chamber 33. As a result, the light irradiated diagonallyupwardly from the light outlet 53 can be reliably received at thelight-receiving element 67 without being interrupted by the ink withinthe ink chamber 33. Enhanced detection accuracy can be thereforerealized at the light-receiving element 67.

Further, the rear wall 34 of the ink cartridge 5, which is positioned ata trailing side in the loading direction, has light-transmissivecharacteristics and light is irradiated from the light outlet 53 towardthe rear wall 34 in the present embodiment. Therefore, when the cover 61is opened, the user can visually confirm how much ink has been left byobserving the light irradiated toward the rear wall 34 that ispositioned close to the user (at a near side of the user).

Further, the pivot-center portion 42 of the first embodiment isstationary positioned within the ink chamber 33 irrespective of theposition of the float 40 (regardless of the pivotal movement of the armmember 31) and the light inlet 50 on which the light from thelight-emitting element 63 is incident is provided on the stationarypivot-center portion 42 to be in confrontation with the light-emittingelement 63.

Suppose that a distance between the arm member 31 and the light-emittingelement 63 may vary due to the pivotal movement of the arm member 31. Inthis case, as the distance is longer, the light emitted from thelight-emitting element 63 becomes harder to be incident on the lightinlet 50 of the arm member 31. Further, since the distance variesdepending on the pivotal movement of the arm member 31, guiding thelight into the arm member 31 reliably and at a constant intensity alsobecomes more difficult, leading to fluctuations of the intensity oflight irradiated from the light outlet 53.

Contrary thereto, since the stationary pivot-center portion 42 is inconfrontation with the light-emitting element 63 in the firstembodiment, the light emitted from the light-emitting element 63 can beconstantly guided to the light outlet 53 via the arm 41, regardless ofthe pivotal movement of the arm member 31.

Further, the pivot-center portion 42 has a spherical shape and thereforethe lower portion of the pivot-center portion 42 on which light from thelight-emitting element 63 is incident (the light inlet 50) has anarcuate-shaped outline projecting toward the light-emitting element 63.With this configuration, the distance between the light inlet 50 and thelight-emitting element 63 can be kept relatively constant, which enablesthe light to be reached at the arm 41 at a stable intensity. Further, inthe present embodiment, the bottom wall 32 is formed with theconcave-shaped surface 32 a that is in confrontation with thepivot-center portion 42. Therefore, the distance between the light inlet50 and the light-emitting element 63 can be made further hard to change.Further, when the convex-shaped pivot-center portion 42 and theconcave-shaped surface 32 a are concentrically positioned with respectto the pivotal center of the arm member 31 (i.e., the shaft 44) as inthe present embodiment, the distance between the light inlet 50 and thelight-emitting element 63 can be made constant regardless of the pivotalmovement of the arm member 31. The pivot-center portion 42 may not beformed to have a spherical shape as a whole, but may only have anarcuate-shaped portion that confronts the light-emitting element 63.

Further, the light-emitting element 63 is provided on the cartridgeloading portion 7, not on the ink cartridge 5. Therefore, the costs ofthe ink cartridge 5 alone can be lowered.

Next, various modifications to the first embodiment will be describedwith reference to FIGS. 4 through 11 wherein like parts and componentsare designated by the same reference numerals as those in the firstembodiment to avoid duplicating description.

An ink cartridge 5A and a cartridge loading portion 7A according to afirst modification of the first embodiment will be described first withreference to FIG. 4.

In the first modification, a light-emitting element 63A is provided at amain body 30A of the ink cartridge 5A, instead of the light-emittingelement 63 of the first embodiment that is provided on the cartridgeloading portion 7.

More specifically, as shown in FIG. 4, the light-emitting element 63A isdisposed within a protruding portion of a bottom wall 32A of the inkcartridge 5A so as to be in confrontation with the light inlet 50 of thepivot-center portion 42. Light emitted from the light-emitting element63A is incident on the light inlet 50 and is guided within the arm 41 toreach the light outlet 53.

With this configuration, the light emitted from the light-emittingelement 63A passes through the main body 30A of the ink cartridge 5Aonly once (when the light is irradiated outside from the light outlet53). In contrast, in the first embodiment, the light emitted from thelight-emitting element 63 needs to pass through the main body 30 of theink cartridge 5 twice, i.e., first the bottom wall 32 and then the rearwall 34, until the light is received at the externally-providedlight-receiving elements 67, 68. However, due to reflection andrefraction, not all of the light emitted from the light-emitting element63 can be received at the light-receiving elements 67, 68. Further, ifthe user happens to contaminate the main body 30 of the ink cartridge 5at the time of handling the ink cartridge 5, the amount of light thatpasses through the main body 30 could also decrease. Therefore, in orderto enhance accuracy of detection, the light should preferably passthrough the main body 30 as less time as possible.

To this effect, according to the configuration of the firstmodification, the light passes the main body 30A of the ink cartridge 5Aonly once, thereby suppressing a decrease in the amount of light thatoccurs when the light passes through the main body 30A of the inkcartridge 5A. As a result, the light irradiated out of the light outlet53 can be easily received externally at the light-receiving elements 67,68.

FIG. 5 shows the ink cartridge 5 and a cartridge loading portion 7Baccording to a second modification of the first embodiment.

In the second modification, the light-receiving elements 67, 68 are notprovided on a cover 61B of the cartridge loading portion 7B, as shown inFIG. 5. In other words, the user can visually confirm the lightirradiated toward outside from the light outlet 53 when the cover 61B isopened. When the cover 61B is formed of a material havinglight-transmissive characteristics, the user can observe the lightirradiated from the light outlet 53 without opening the cover 61B.

Further, even if the light-receiving elements 67, 68 are provided as inthe first embodiment, the user can visually observe transition of theposition of the irradiated light while the float 40 and the protrudingportion 43 move from the light-receiving element 67 to thelight-receiving element 68.

FIG. 6 shows the ink cartridge 5 and a cartridge loading portion 7Caccording to a third modification of the first embodiment.

In the third modification, the light-receiving element 67 is dispensedwith, while the light-receiving element 68 is provided on a cover 61C ofthe cartridge loading portion 7C, as shown in FIG. 6. With thisconfiguration, not only whether the residual amount of ink is more thana predetermined amount can be electrically detected (in case of FIG. 6,whether or not there is little amount of ink in the ink chamber 33 canbe detected), the user can also confirm intermediate fill levels of theink in the ink chamber 33 by visually observing the current position ofthe float 40.

A cartridge loading portion 7D) according to a fourth modification ofthe first embodiment will be described next. In the cartridge loadingportion 7D, the ink cartridge 5 according to the first embodiment isaccommodated.

In the fourth modification, user's visual confirmation of the light isalso assumed. A cover 61D of the cartridge loading portion 7D has atleast a portion that can transmit light. Specifically, thislight-transmissive portion is arranged at a position on the cover 61D incoincidence with the rear wall 34 of the ink cartridge 5 (especially,the portion of the rear wall 34 from which the light from the lightoutlet 53 is emanated) when the cover 61D is closed. Thelight-transmissive portion may be formed of a material havinglight-transmissive characteristics, or may be a slit formed on the cover61D. The rear wall 34 corresponds to a first wall, and the cover 61Dcorresponds to a cover having a portion with light-transmissivecharacteristics of the present invention.

With this configuration, even when the cover 61D is closed, the lightfrom the light outlet 53 can be observed from outside through thelight-transmissive portion of the cover 61D. Therefore, the user canconfirm the residual amount of the ink within the ink cartridge 5 evenwhen the cover 61D is closed.

FIG. 7 shows an ink cartridge 5E and a cartridge loading portion 7Eaccording to a fifth modification of the first embodiment.

In the fifth modification, the amount of light irradiated from the lightoutlet 53 is made variant depending on the position of the float 40 (theprotruding portion 43). Therefore, the user can be readily informedabout the residual amount of ink based on the intensity of lightirradiated from the light outlet 53, in addition to the position of thelight.

More specifically, as shown in FIG. 7, a rear wall 34E of the inkcartridge 5E is formed to have a thickness that becomes smaller as therear wall 34E extends upward in the vertical direction. Thisconstruction allows stronger light to be irradiated outside when theresidual amount of ink is larger, while allowing lesser light to beirradiated as the residual amount of ink is smaller. Alternatively, therear wall 34E may be formed to have a thickness that becomes smaller asthe rear wall 34E extends downward in the vertical direction. In thiscase, stronger amount of light can be irradiated as the residual amountof ink is smaller, so that the user can be warned that the residualamount of ink is getting smaller.

Still alternatively, when a cover 61E is made of a light-transmissivematerial, the cover 61E may have a thickness that varies with respect tothe vertical direction. With this configuration as well, due to thevariation of the thickness of the cover 61E in the vertical direction,how much amount of light can be transmitted through the cover 61E can bealso made variant.

Further alternatively, how much light can be transmitted through therear wall 34E and the cover 61E can also be made variant with respect tothe vertical direction by: fabricating the rear wall 34E or the cover61E from materials having different light-transmissive capabilities fromone another (for example, different types of synthetic resin); orpartially attaching a film (capable of lowering translucency) to therear wall 34E or the cover 61E; or alternatively by differentiating adistance between the light outlet 53 and the rear wall 34E.

A cartridge loading portion 7F according to a sixth modification of thefirst embodiment will then be described.

In the six modification, a light-emitting element 63F of the cartridgeloading portion 7F functions to emit white light. As the light-emittingelement 63F emitting white-colored light, a well-known white-color LED,an incandescent bulb, or a fluorescent bulb is available.

Since each ink cartridge 5 stores ink of a different color, when thewhite light emitted from the light-emitting element 63F is irradiatedtoward outside of the ink cartridge 5, the white light reflects thecolor of the ink existing between the light outlet 53 and the rear wall34 of the ink cartridge 5. The irradiated light has therefore the samecolor as that of the ink. With this configuration, by looking at thecolor of the irradiated light, the user can confirm the color of the inkstored in each ink cartridge 5.

It should be noted that, when the light from the light outlet 53 isirradiated substantially upward as shown in FIG. 3A, the layer of airinevitably exists between the light outlet 53 and the rear wall 34 (themain body 30). In this case, the white light emitted from thelight-emitting element 63F is never colored when exiting out of the mainbody 30. Therefore, in the sixth modification, the light from the lightoutlet 53 should be preferably irradiated in a substantially horizontaldirection or downward so that the ink can be reliably interposed betweenthe light outlet 53 and the rear wall 34.

FIG. 8 shows an ink cartridge 5G and a cartridge loading portion 7Gaccording to a seventh modification of the first embodiment.

In the seventh modification, a float 40G is provided with two protrudingportions 43 a, 43 b. The protruding portions 43 a, 43 b have lightoutlets 53 a, 53 b respectively from each of which the light emittedfrom the light-emitting element 63 is irradiated. When there is asufficient amount of ink in the ink chamber 33 as shown in FIG. 8, thelight outlet 53 a is in opposition to the rear wall 34 of the main body30, while the light outlet 53 b is in opposition to the upper wall 35 ofthe main body 30. When the main body 30 as a whole is formed of amaterial having light-transmission capability as in the firstembodiment, the upper wall 35 can transmit light. Therefore, the lighttraveling through an arm member 31 is irradiated from the light outlets53 a, 53 b toward outside in two different directions via the rear wall34 and the upper wall 35, as indicated by heavy lines in FIG. 8.

In this way, two beams of light can be simultaneously irradiated outwardof the main body 30 from the two light outlets 53 a, 53 b. Therefore,each beam of light can be utilized for two different purposes.

In the seventh modification, a light-receiving element 67G is disposedat an upper wall section 690 of the cartridge loading portion 70 toenable the light-receiving element 67G to detect the light irradiatedfrom the light outlet 53 b. The light irradiated from the light outlet53 a can be used for user's visual confirmation of the residual amountof ink within the ink cartridge 5G.

When the light-receiving element 670 is not provided on the upper wallsection 69G, both beams of light from the light outlet 53 a, 53 b may beused for user's visual confirmation on the residual amount of ink withinthe ink cartridge 50. In this case, since the user checks the amount ofink not only from rearward but also from above (through the upper wallsection 69G), the upper wall section 69G should be formed of alight-transmissive material or be provided with either a window or acut-out through which the user can actually observe the irradiatedlight.

An ink cartridge 5H and a cartridge loading portion 7H according to aneighth modification of the first embodiment will be described next.

In the eighth modification, the light irradiated from the light outlet53 is designed to be emanated from any one of walls, other than the rearwall 34, constituting a main body 30H of the ink cartridge 5H. Alight-receiving element 68H is therefore disposed on a wall section ofthe cartridge loading portion 7H that faces the wall of the main body30H from which the light is emanated. For example, if the light isirradiated outside through a front wall 36H of the main body 30H, thelight-receiving element 68H is disposed on a front wall section 65H ofthe cartridge loading portion 7H. In this case, since thelight-receiving element 68H is positioned at a deeper side from the user(frontward in the loading direction), the user is unlikely to contactthe light-receiving element 68H.

FIG. 9 shows an ink cartridge 5I and a cartridge loading portion 7Iaccording to a ninth modification of the first embodiment.

Contrary to the first embodiment where the pivot-center portion 42 isdisposed in the vicinity of the bottom wall 32 of the main body 30, apivot-center portion 42I of an arm member 31I of the ninth modificationis disposed at a position adjacent to an upper wall 35I of a main body30T. More specifically, as shown in FIG. 9, the pivot-center portion 42Iis arranged at a position in the vertical direction substantially thesame as that of a float 40I which is held at its upper-limit position. Alight-emitting element 63I is disposed on an upper wall section 69I ofthe cartridge loading portion 7I. The pivot-center portion 42I isarranged to be in confrontation with the light-emitting element 63I sothat light from the light-emitting element 63I can be incident on alight inlet 50I.

With this configuration, even when a sufficient amount of ink is left inthe ink cartridge 5I, the layer of air is available between the upperwall 35I and the ink (the liquid surface of the ink). This means thatair is interposed between the light inlet 50I of the pivot-centerportion 42I and the light-emitting element 63I, and therefore the lightemitted from the light-emitting element 63I can be reliably reached atthe light inlet 50I.

Further, a cover 61I has an upper end that is pivotally movablysupported to the upper wall section 69I, as shown in FIG. 9. Therefore,the user needs to open the cover 61I from below. This configurationcontributes to prevention of the user contact with the light-receivingelements 67I, 68I disposed on an inner surface of the cover 61I. Itshould be noted, however, that this configuration of the cover 61I (thecover 61I is opened from its bottom side) may possibly become anobstacle for installation/removal of the ink cartridge 5I and/or for theuser's visual observation of the residual amount of ink (the position ofthe float 40I). In this point of view, the configuration of the cover 61according to the first embodiment (the cover 61 is opened from its topside) is preferable to that of the cover 61I of the ninth modification.

FIG. 10 shows an ink cartridge 5J according to a tenth modification ofthe first embodiment and the cartridge loading portion 7.

In the tenth modification, an arm 41J of an arm member 31J has one endon which a light inlet 50J is formed and has another end to which afloat 40J is connected. A pivot-center portion 42J is arranged on thearm 41J at a position midway between the light inlet 50J and the float40J. The light inlet 50J provided at the one end of the arm 41J isadapted to face the light-emitting element 63 formed on the bottom wallsection 66 of the cartridge loading portion. However, in the tenthmodification, since the arm member 31J pivotally moves about a shaft 44Jof the pivot-center portion 42J in accordance with the position of thefloat 40J, a distance between the light inlet 50J and the light-emittingelement 63 varies depending on the position of the float 40J.

More specifically, as the amount of ink in the ink chamber 33 decreases,the arm member 31J pivotally moves about the shaft 44J in a clockwisedirection in FIG. 10 due to the downward movement of the float 40J.Since the light inlet 50J moves in conjunction with the movement of thearm member 31J, the distance between the light inlet 50J and thelight-emitting element 63 is subjected to change. Therefore, the amountof light guided from the light inlet 50J to a light outlet 53Jinevitably changes. That is, the amount of light irradiated outward fromthe light outlet 53J changes in accordance with the residual amount ofink. The user can be advised of how much ink remains in the inkcartridge 5J by checking the intensity of light coming out of the inkcartridge 5J, in addition to by visually confirming the position of thefloat 40J.

In the tenth modification, as shown in FIG. 10, the distance between thelight inlet 50J and the light-emitting element 63 is small when asufficient amount of ink is left in the ink chamber 33. Therefore, theamount of light irradiated outward from the light outlet 53J is large.As the ink decreases, the amount of light irradiated out of the lightoutlet 53J becomes smaller since the distance between the light inlet50J and the light-emitting element 63 becomes longer. However,alternatively, the amount of light irradiated outward of the inkcartridge 5J may be configured to increase as the residual amount of inkdecreases. In this case, the distance between the light inlet 50J andthe light-emitting element 63 is designed to be smaller in accordancewith decrease in the residual amount of ink. Specifically, thelight-emitting element 63 may be arranged at the front wall section 65at a position above the ink outlet port 37. With this configuration,when the float 40J moves down as the ink decreases (a state shown by adouble-dotted chain line in FIG. 10), the light inlet 50J is movedupward to be closer to the light-emitting element 63 disposed at thefront wall section 65. Therefore, the amount of light guided within thearm member 31J, i.e., the amount of light irradiated outside from thelight outlet 53J increases.

FIG. 11 shows an ink cartridge 5K and a cartridge loading portion 7Kaccording to an eleventh modification of the first embodiment.

In the eleventh modification, the arm member 31 of the first embodimentis dispensed with and a float 40K alone is vertically movably providedwithin an ink chamber 33K of the ink cartridge 5K. A guide portion 70 isdisposed within the ink chamber 33K so as to guide the float 40K tovertically move along a rear wall 34K of the ink cartridge 5K. A lightoutlet 53K is provided at the float 40K.

A light-emitting element 63K is disposed at a bottom wall section 66K ofthe cartridge loading portion 7K and light-receiving elements 67K, 68Kare arranged at an inner surface of a cover 61K. In order to guide thelight emitted from the light-emitting element 63K to the light outlet53K of the float 40K, an optical fiber cable 71 is used for connectingthe light outlet 53K and the light-emitting element 63K. The opticalfiber cable 71 corresponds to the light guiding portion of the presentinvention.

More specifically, the optical fiber cable 71 has one end positioned ata bottom wall 32K of a main body 30K of the ink cartridge 5K forreceiving light from the light-emitting element 63K disposed on thebottom wall section 66K. The optical fiber cable 71 has another endarranged in the vicinity of the light outlet 53K of the float 40K sothat the light from the light-emitting element 63K can be reliablyguided to the light outlet 53K.

The another end of the optical fiber cable 71 may not necessarily beinserted within the float 40K, but may be attached to an outer surfaceof the float 40K. In this case, the light guided to the float 40Kthrough the optical fiber cable 71 is directly irradiated toward therear wall 34K without traversing the float 40K.

An ink cartridge 205 and a cartridge loading portion 207 according to asecond embodiment will be described next with reference to FIGS. 12 to13B. The ink cartridge 205 of the second embodiment has a configurationidentical to that of the ink cartridge 5 of the first embodiment exceptthat a protruding portion 243 is provided with a light-emitting element263. Like parts and components are designated by the same referencenumerals as those of the first embodiment to avoid duplicatingdescription.

As shown in FIGS. 12 through 13B, the ink cartridge 205 includes a mainbody 230 defining the ink chamber 33 therein and an arm member 231provided within the ink chamber 33 for detecting residual amounts ofink.

The arm member 231 is different from the arm member 31 of the firstembodiment in that the light-emitting element 263 is arranged within theprotruding portion 243. Therefore, no light-emitting element is providedat the cartridge loading portion 207. The protruding portion 243 has atip end having light-transmissive characteristics so that the tip endcan serve as a light outlet 253 from which light emitted from thelight-emitting element 263 can be irradiated outward. Thus, the lightemitted the light-emitting element 263 can be irradiated outside of themain body 230 through the rear wall 34 that can transmit light.

As in the first embodiment, the light-receiving elements 67, 68 areadapted to receive the light irradiated from the light outlet 253 thatmoves in accordance with the residual amount of ink within the inkchamber 33. Therefore, two positions of a float 240, i.e., the inkremaining in the ink chamber 33 can be detected at two levels at theinkjet printer 1. If more than three light-receiving elements areprovided on the cartridge loading portion 207, the residual amount ofink can be detected at more than three levels.

Further, in the second embodiment, the light-emitting element 263 isdisposed at the protruding portion 243 movable in conjunction with thefloat 240. Since the light irradiated from the light outlet 253 can passthrough the main body 230 only once until the light exits outside of themain body 230, reduction in the amount of light that inevitably occurswhen the light passes through the main body 230 can be suppressedcompared to a conventional ink cartridge in which light needs to passtherethrough twice. Therefore, the light coming out of the ink cartridge205 can be detected easily at the cartridge loading portion 207.

In the second embodiment, since the light-emitting element 263 ispositioned at the protruding portion 243 that is provided within the inkchamber 33, an electrical connection is required to supply power fromthe cartridge loading portion 207 to the light-emitting element 263. Forexample, wirings for supplying power may be provided from an outersurface of the ink cartridge 205 to the light-emitting element 263 viathe shaft 44 and an internal space formed within the arm member 231.Alternatively, a primary coil may be disposed on the cartridge loadingportion 207, while a secondary coil connected to the light-emittingelement 263 may be disposed on the ink cartridge 205. For example, thesecondary coil may be disposed within the float 240 or the protrudingportion 243. In this case, application of electricity to the primarycoil causes a magnetic field between the primary coil and the secondarycoil to change, generating an induced current across the secondary coil.

The light-emitting element 263 may not necessarily be disposed withinthe protruding portion 243 as in the second embodiment, but may beattached to an outer surface of the float 240 or the protruding portion243. In this case, the light emitted from the light-emitting element 263does not travel through walls of the float 240 or the protruding portion243, but is irradiated directly toward the rear wall 34 of the main body230.

Various modifications to the second embodiment are also conceivable.

To the ink cartridge 205 of the second embodiment, modifications made tothe ink cartridge 5 of the first embodiment may also be applicable. Forexample, omission of the light-receiving elements 67, 68 (second andthird modifications: FIGS. 5 and 6); change in light-transmission statusof the cover 61 (the covers 61D, 61E of the fourth and fifthmodifications: FIG. 7); provision of the light-emitting element thatemits white light (the light-emitting element 63F of the sixthmodification) can also be applicable to the ink cartridge 205 of thesecond embodiment.

FIG. 14 shows an ink cartridge 205G and a cartridge loading portion 207Gaccording to a variation of the second embodiment in which the seventhmodification to the first embodiment is applied to the ink cartridge 205and the cartridge loading portion 207 of the second embodiment. A float240G has two protruding portions 243 a, 243 b which accommodate thereinlight-emitting element 263 a, 263 b respectively. The protrudingportions 243 a, 243 b are respectively formed with light outlets 253 a,253 b in correspondence with the light-emitting elements 263 a, 263 b.

When the ink is sufficient in the ink chamber 33, light from thelight-emitting elements 263 a, 263 b is irradiated from the light outlet253 a, 253 b outward via the rear wall 34 and the upper wall 35 that cantransmit light therethrough. The light irradiated from the light outlet253 a is visually confirmed by the user through the rear wall 34, whilethe light irradiated from the light outlet 253 b is electricallydetected by a light-receiving element 267G disposed at an upper wallsection 2690 of the cartridge loading portion 207G.

The following modifications made to the ink cartridge 5 of the firstembodiment can also be applied to the ink cartridge 205 of the secondembodiment: change in the direction of light irradiated outward from thelight outlet 53 (eighth modification); change in the position of thepivot-center portion 42 within the ink chamber 33 (the pivot-centerportion 42I of the ninth modification: FIG. 9); change in the positionof the pivot-center portion 42 at the arm member 31 (the pivot-centerportion 42J of the tenth modification: FIG. 10); and change in theconfiguration of the float 40 (the float 40K of the eleventhmodification: FIG. 11).

Other modifications can also be made to the ink cartridge 5 of the firstembodiment and to the ink cartridge 205 of the second embodiment.

For example, the main body 30 according to the first embodiment and themain body 230 of the second embodiment are, as a whole, formed of amaterial capable of transmitting light, such as synthetic resin.However, only a portion of the main bodies 30(230) where lightirradiated from the light outlets 53(253) passes through may be allowedto transmit the irradiated light. For example, in case of the main body30 of the first embodiment shown in FIG. 3, only portions of the rearwall 34 that are in confrontation with the light-receiving elements 67,68 of the cover 61 can be made of a material of light transmissivecharacteristics, while remaining portions of the rear wall 34 may havecharacteristics to block light.

Further, the loading direction of the ink cartridge is not necessary tobe horizontal, but may be a direction other than horizontal direction.For example, the present invention may also be applicable to an inkcartridge that is mounted in the vertical direction.

A member adapted to move in accordance with the residual amount of inkand to irradiate light outward is not limited to a float that moves inthe vertical direction as in the first and second embodiments, providedthat the member moves according to a variation of the amount of ink. Forexample, a float that vertically moves in accordance with residualamounts of ink may be connected to a moving member within an inkchamber. The moving member is allowed to move in a prescribed directiondifferent from the vertical direction in which the float moves, due tosome kind of direction conversion mechanism that can convert thevertical movement of the float into the movement of the moving member inthe prescribed direction. Such a mechanism may be configured ofwell-known mechanical elements, such as a link mechanism or apivotally-moving mechanism.

The present embodiment has been applied to an ink cartridge to be usedin an inkjet printer in the above-described embodiments. However, thepresent invention can also be applied to other cartridges, regardless oftypes of liquid stored in the cartridges or intended purposes of thecartridges, as long as such cartridges are provided with a main body forstoring liquid therein and a moving member that moves in accordance withan amount of the liquid within the main body.

While the invention has been described in detail with reference to theembodiments thereof, it would be apparent to those skilled in the artthat various changes and modifications may be made therein withoutdeparting from the scope of the invention.

What is claimed is:
 1. A liquid cartridge detachably loadable in acartridge loading section of a liquid supplying device, the liquidcartridge comprising: a main body defining therewithin a liquidaccommodation chamber storing liquid therein, the liquid accommodationchamber having a light-transmission portion transmitting lighttherethrough; an arm-like shaped moving member disposed within theliquid accommodation chamber and pivotally movably supported by the mainbody to be pivotally movable in accordance with an amount of the liquid,the moving member having one end and another end opposite to the oneend; a light-emitting element provided at the one end of the movingmember and configured to emit light and move in conjunction with thepivotal movement of the moving member; and a light outlet configured toirradiate the light emitted from the light-emitting element towardoutside of the main body via the light-transmission portion.
 2. Theliquid cartridge according to claim 1, wherein the liquid accommodationchamber is formed with two light-transmission portions at two differentpositions, and the light outlet is configured of two light exits eachconfronting each of the two light-transmission portions simultaneously,each light exit irradiating the light emitted from the light-emittingelement outside of the main body via the correspondinglight-transmission portion.
 3. The liquid cartridge according to claim1, wherein the light outlet is configured to irradiate the light emittedfrom the light-emitting element toward outside of the main body via aposition on the light-transmission portion, the position varying inaccordance with the amount of the liquid in the liquid accommodationchamber.
 4. The liquid cartridge according to claim 1, wherein the mainbody has a first wall formed with a liquid outlet port through which theliquid in the liquid accommodation chamber is configured to flow outtherefrom; and wherein the light from the light outlet is irradiated ina direction parallel to a plane perpendicular to the first wall and inwhich the light outlet moves in accordance with the amount of theliquid.
 5. A liquid supplying device comprising: a liquid cartridge; anda cartridge loading section configured to accommodate therein the liquidcartridge, the liquid cartridge including: a main body definingtherewithin a liquid accommodation chamber storing liquid therein, theliquid accommodation chamber having a light-transmission portiontransmitting light therethrough; an arm-like shaped moving memberdisposed within the liquid accommodation chamber and pivotally movablysupported by the main body to be pivotally movable in accordance with anamount of the liquid, the moving member having one end and another endopposite to the one end; a light-emitting element provided at the oneend of the moving member and configured to emit light and move inconjunction with the pivotal movement of the moving member; and a lightoutlet configured to irradiate the light emitted from the light-emittingelement toward outside of the main body via the light-transmissionportion.